Various electronic equipment is mounted on a motor vehicle as a mobile unit. Therefore, a motor vehicle is provided with a wiring harness for supplying an electric power from an electric source to electronic equipment and for transferring control signals and so on from a computer to electronic equipment. The wiring harness includes a plurality of electric wires 106 (shown in FIG. 14) as articles, electric connectors, each being attached to an end of the wire 106, and so on.
The wire 106 includes an electrically conductive core wire 105 (shown in FIG. 14) and a coating made of insulating synthetic resin, which coats the core wire 105. The wire 106 is so-called a coated wire. The wire 106 has been produced by using a producing device 100 shown in FIG. 14, which includes a supply unit 101, extrusion-coating unit 102, cooling water bath 103 and winding unit 104.
Upon producing the wire 106, the producing device 100 transfers a core wire 105 or a wire 106 in turn through the supply unit 101, extrusion-coating unit 102, cooling water bath 103 and winding unit 104. The device 100 has a plurality of pulleys 107 to transfer the core wire 105 or wire 106.
The supply unit 101 supplies the core wire 105 which has no coating thereon. The extrusion-coating unit 102 extrudes the insulating synthetic resin onto the circumference of the core wire 105 supplied from the supply unit 101, forming the coating. The cooling water bath 103 cools the coating. The winding unit 104 cuts the wire 106 into a specific length and winds the cut wire 106 around a drum or the like placing the wire 106 in a condition of being shipped. Thus, the producing device 100 produces the wire 106.
A connector includes an electrically conductive terminal fitting and an insulating connector housing. The terminal fitting is attached to an end of the wire 106 and electrically connected to the core wire 105 of the wire 106. The connector housing is formed into a box-shape and receives the terminal fitting.
Upon assembling a wiring harness, first the wire 106 is cut into a specific length and thereafter a terminal fitting is attached to an end of the wire 106. The wires 106 are connected to each other according to the need. Thereafter, the terminal fitting is inserted into the connector housing, thereby assembling the wiring harness.
As for the wire 106 of the wiring harness, the size of the core wire 105, the material of the coating (for possible change in the material depending on heat-resisting property), and a purpose of use must be distinguished. Here, the purpose of use means a control signal for an air-bag, antilock brake system and vehicle speed information, and a vehicle system in which the wire 106 in a power transmission system is used.
So far, in order to distinguish the purpose of use as described above, an outer surface of the wire 106 of the wiring harness is formed in a stripe pattern with two different colors. In a conventional producing device 100 as shown in FIG. 14, in an extrusion-coating unit 102, a coloring agent is added into the synthetic resin which constitutes the coating. Then, in the extrusion-coating unit 102, the synthetic resin is mixed with the coloring agent so as to make the color of the synthetic resin be the same as that of the coloring agent. Then, the synthetic resin having the same color as that of the coloring agent is extrusion-coated onto the circumference of the core wire 105. Further, a part of the outer surface of the wire 106 is colored with a color different from the color of the coloring agent, thereby coloring the wire 106 into a stripe pattern.
A maker of motor vehicles receives various demands from users. That is, a motor vehicle is forced to have various electronic equipment therein. Accordingly, the wiring harness needs many types of the wire 106, such as a hundred of types of the wire 106. In this case, the wires 106 having various colors are needed. Therefore, the producing device 100 must frequently change the color of the coating of the wire 106.
In the conventional producing device 100 as shown in FIG. 14, upon changing the color of the coating (that is, the color of the wire 106), the extrusion-coating unit 102 is halted once and then, the coloring agent to be mixed with the synthetic resin is changed. In this case, when the wires 106 having various colors are produced, the extrusion-coating unit 102 must be halted frequently, causing the deterioration in the production efficiency of the wire 106.
Therefore, a method has been proposed, in which the coloring agent to be added to the synthetic resin is changed with the extrusion-coating unit 102 being kept in operation. When the coloring agent is changed with the extrusion-coating unit 102 being kept in operation, immediately after changing the coloring agent, the synthetic resin is mixed with both the coloring agent before the change and the coloring agent after the change, resulting in that the color of the coating becomes a mixed color of the color of the coloring agent before the change and that of the coloring agent after the change. The wire 106 having such a mixed color cannot be used for making a wiring harness because the mixed color is not a desired color to be used in the system described above. That is, when the coloring agent is changed with the extrusion-coating unit 102 being kept in operation, the resulted wire 106 has inevitably a portion which cannot be used to make a wiring harness, causing the deterioration in the yield of the material of the wire 106. Further, a part of the outer surface cannot be easily changed to a color which is different from the color of the coloring agent.
Thus, with the conventional producing device, it has been difficult to change a color of a mark, which is formed on the outer surface of the wire, without deteriorating the production efficiency of the wire as an article.
It is therefore an objective of the present invention to provide a method and device for automatically marking an article, by which the deterioration in the yield can be prevented from occurring and a color of a mark to be formed on the article can be easily changed.